JPH0334716B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention generates an electron beam for each division when a screen on a screen is vertically divided into a plurality of divisions, and generates an electron beam for each subdivision. The present invention relates to an apparatus for displaying a plurality of lines by vertically deflecting a beam to display a television image as a whole.

Conventional technology Conventionally, cathode ray tubes have been mainly used as display elements for color television image display, but conventional cathode ray tubes have a very long depth compared to the screen size, making it difficult to receive thin television images. It was impossible to create a machine. In addition, recently, KL display elements, plasma display devices, liquid crystal display elements, etc. have been developed as flat display elements.
All of them are insufficient in terms of performance such as brightness, contrast, and color display.

Therefore, a new display device was proposed in Japanese Patent Application No. 56-20618 (Japanese Unexamined Patent Publication No. 135590-1982) to achieve a flat display device using electron beams.

This method generates an electron beam for each section when the screen is vertically divided into multiple sections, and displays multiple lines by deflecting the electron beam vertically for each section. ,
It displays the television image as a whole.

First, a basic configuration example of the image display element used here will be explained with reference to FIG.

This display element is arranged in order from the back to the front.
A back electrode 1, a line cathode 2 as a beam source, a vertical focusing electrode 3, 3' vertical deflection electrode 4, a horizontal focusing electrode 6,
A horizontal deflection electrode 7, a beam accelerating electrode 8, and a screen plate 9 are arranged, and these are housed in the evacuated interior of a flat glass bulb (not shown). A line cathode 2 serving as a beam source is stretched horizontally so as to generate an electron beam distributed linearly in the horizontal direction, and a plurality of line cathodes 2 (here, 2 A to 2 D are shown). In this embodiment, it is assumed that 15 pieces are provided. Let's call them 2i~2yo. These wire cathodes 2 are constructed by coating the surface of a tungsten wire with a diameter of 10 to 20 μΦ with an oxide cathode material for thermionic emission. These line cathodes 2A to 2Y are heated so as to generate a thermionic electron beam by passing an electric current through them, and as will be described later, the electron beams are generated sequentially for a certain period of time starting from the line cathode 2I. controlled to emit. The back electrode 1 suppresses generation of electron beams from line cathodes 2 other than the line cathode 2 that is controlled to emit electron beams for a certain period of time, and directs the generated electron beams only in the forward direction. It has the effect of pushing out. The back electrode 1 may be formed by applying a conductive material to the inner surface of the rear wall of the glass bulb. In addition, the line cathode 2 of these back electrodes 1
Instead, a planar electron beam emitting cathode may be used.

The vertical focusing electrode 3 is a conductive plate 11 having a horizontally long slit 10 facing each of the line cathodes 2a to 2y. focus in a direction. An electron beam for one horizontal line (360 pixels) is extracted at the same time. In the figure, only one section in the horizontal direction is shown. The slit 10 may be provided with crosspieces at appropriate intervals in the middle, or may be substantially configured as a slit by a row of many through holes arranged horizontally at small intervals (nearly touching intervals). may have been done. The vertical focusing electrode 3' is also similar.

A plurality of vertical deflection electrodes 4 are arranged horizontally at intermediate positions of the switches 10, and conductors 13 and 13' are provided on the upper and lower surfaces of the insulating substrate 12, respectively. It is configured. And the opposing conductors 13, 13'
A vertical deflection voltage is applied between them to deflect the electron beam in the vertical direction. In this embodiment, the electron beam from one line cathode 2 is vertically deflected to positions corresponding to 16 lines by a pair of conductors 13, 13'. And, by 16 vertical deflection electrodes 4, 15
Fifteen pairs of conductors are constructed, one for each of the line cathodes 2, and the electron beam is deflected to draw 240 horizontal lines on the screen 9.

Next, the control electrodes 5 are composed of conductive plates 15 each having a vertically long slit 14, and a plurality of control electrodes 15 are arranged in parallel in the horizontal direction at predetermined intervals. In this embodiment, 180 conductive plates 15a to 15n for control electrodes are provided (only nine are shown in the figure). Each of the control electrodes 5 separates and extracts the electron beam into two picture elements in the horizontal direction, and controls the amount of electron beam passing therethrough in accordance with a video signal for displaying each picture element. Therefore, the conductive plates 15a to 15n for the control electrode 5 are
With this arrangement, 360 pixels can be displayed per horizontal line. In addition, in order to display images in color, each picture element is displayed using phosphors of three colors, R, G, and B, and each control electrode 5 has each of the R, G, and B colors corresponding to two picture elements. Video signals are added sequentially. In addition, 180 conductive plates 15a to 15n for control electrodes 5
180 sets of video signals for one line (two picture elements per set) are simultaneously applied to each of the lines, and one line of video is displayed at one time.

The horizontal focusing electrode 6 is composed of a conductive plate 17 having a plurality of vertically long slits 16 (180 slits 16) facing the slits 14 of the control electrode 5, and collects electrons for each picture element divided in the horizontal direction. Each beam is focused horizontally into a narrow electron beam.

The horizontal deflection electrode 7 is made up of a plurality of conductive plates 18, 18' arranged vertically on both sides of the slit 16, and each electrode 18, 18' has six levels of horizontal deflection. A voltage is applied to horizontally deflect the electron beam for each pixel, and on the screen 9 two sets of R,
The G and B phosphors are sequentially irradiated to emit light. In this embodiment, the deflection range is two picture elements wide for each electron beam.

The accelerating electrode 8 is composed of a plurality of conductive plates 19 provided horizontally at the same position as the vertical deflection electrode 4, and accelerates the electron beam with sufficient energy so that it collides with the screen 9'.

The screen 9 is constructed by coating the back surface of a glass plate 21 with a phosphor 20 that emits light when irradiated with an electron beam, and adding a metal back layer (not shown). The phosphor 20 is arranged for each slit 14 of the control electrode 5, that is, for each horizontally divided electron beam.
Two pairs of three-color phosphors, R, G, and B, are provided and are applied in stripes in the vertical direction. In FIG. 1, the broken lines drawn on the screen 9 indicate divisions in the vertical direction that are displayed corresponding to each of the plurality of line cathodes 2, and the two-dot chain lines correspond to each of the plurality of control electrodes 5. Indicates the horizontal division displayed. As shown in the enlarged view in Figure 6, one section partitioned by these two has R, G, and B phosphors 20 for two pixels in the horizontal direction, and 16 lines in the vertical direction. It has a width.
For example, the size of one section is 1 in the horizontal direction.
mm, and the vertical direction is 10 mm.

Note that in FIG. 5, the length in the horizontal direction is greatly enlarged relative to the length in the vertical direction for clarity.

In addition, in this embodiment, only one pair of R, G, and B phosphors 20 for two picture elements are provided for one control electrode 5, that is, one electron beam, but of course, one picture element Alternatively, three or more picture elements may be provided. In that case, R, G, and B video signals for one picture element or three or more picture elements are sequentially applied to the control electrode 5, and the horizontal deflection is synchronously applied to the control electrode 5. It will be done.

Next, the basic configuration of a drive circuit for displaying television images on this display element will be explained with reference to FIG. First, a driving portion for irradiating the screen 9 with an electron beam to emit raster light will be described.

The power supply circuit 22 is a circuit for applying a predetermined bias voltage (operating voltage) to each electrode of the display element,
−V ₁ to the back electrode 1, and −V 1 to the vertical focusing electrodes 3, 3.
DC voltages of V ₃ , V ₃ ', V ₆ to the horizontal focusing electrode 6, V ₈ to the accelerating electrode 8, and V ₉ to the screen 9 are applied.

Next, the composite video signal of the television signal is applied to the input terminal 23, and the synchronization separation circuit 24 separates and extracts the vertical synchronization signal V and the horizontal synchronization signal H.

The vertical deflection drive circuit 40 includes a vertical deflection counter 25, a memory 27 for storing vertical deflection signals, and a digital-to-analog converter 39 (hereinafter referred to as a DA converter). As input pulses to the vertical deflection drive circuit 40, a vertical synchronizing signal V and a horizontal synchronizing signal H shown in FIG. 8 are used. The vertical deflection counter 25 (8 bits) receives the vertical synchronization signal V.
The horizontal synchronizing signal H is counted. This vertical deflection counter 25 counts the effective scanning period (here, a period of 240 hours) excluding the vertical retrace period of the vertical period,
This count output is supplied to an address in memory 27. The memory 27 outputs vertical deflection signal data (here, 10 bits) corresponding to each address, and the D-A converter 39 outputs the data of the vertical deflection signal as shown in FIG.
V′ is converted into a vertical deflection signal. In this circuit
There is a memory address that stores the vertical deflection signal corresponding to each line of 240H, and by storing regular data in the memory every 16H, it is possible to obtain 16 levels of vertical deflection signals.

On the other hand, the line cathode drive circuit 26 receives the vertical synchronization signal V
Line cathode drive pulses [I to Y] are created using the output of the vertical deflection counter 25. FIG. 9a shows the relationship between the vertical synchronizing signal V, the horizontal synchronizing signal H, and the lower five bits of the vertical deflection counter 25. FIG. 9b shows a method of creating line cathode drive pulses [A' to Y'] every 16H using these signals. In Figure 9, LSB indicates the lowest bit, (LSB+1)
means the bit one higher than the LSB.

The first line cathode drive pulse [A'] can be created by an R-S flip-flop using the vertical synchronization signal V and the output (LSB+4) of the vertical deflection counter 25, and the line cathode drive pulse [A'~ y'] uses a shift register to transfer the line cathode drive pulse [a'] to the vertical deflection counter 25.
This can be obtained by using the inverted version of the output (LSB+3) as the clock and transferring it. These driving pulses [A' to YO'] are inverted so that the potential is low only during each pulse period, and the line cathode driving pulses [A to YO'] are set to a high potential of about 20 volts during other periods.
y] and added to each line cathode 2i to 2yo.

Each line cathode 2i~2yo has its driving pulse [i~
During the high potential period of drive pulses [Y], a current is passed to heat it, and the heated state is maintained so that electrons can be emitted during the low potential period of drive pulses [Y]. As a result, a low potential drive pulse [I to YO] is applied to each of the 15 line cathodes 2I to 2Y at 16H.
Electrons are released only during this period. During the period when a high potential is applied, the potential at the line cathode 2 is lower than the potential at the position of the line cathode 2 determined by the back current 1 and the bias voltage applied to the vertical focusing electrode 3. Since the applied high potential becomes positive, no electrons are emitted from the line cathodes 2I to 2Y. Thus, in the line cathode 2, electrons are sequentially emitted from the upper line cathode 2a toward the lower line cathode 2y every 16H period during the effective vertical scanning period.

The emitted electrons are pushed forward by the back electrode 1, pass through the opposing slits 10 of the vertical focusing electrode 3, and are focused in the vertical direction to form a flat electron beam.

Next, the relationship between the line cathode drive pulses [I to Y] and the vertical deflection signals V and V' will be explained with reference to FIG. The vertical deflection signals V, V' change by 1H during the 16H period of each line cathode pulse [I to Y], and change in 16 steps. The vertical deflection signals V and V′ both have a center voltage of V ₄ , and V increases sequentially,
V′ is configured to change in opposite directions so as to decrease sequentially. These vertical deflection signals V and V' are applied to the vertical deflection electrode 4 electrodes 13 and 13', respectively, and as a result, the line cathode 2
The electron beam generated from I~2Yo is vertically
It is deflected in 16 steps, and as mentioned earlier, on the screen 9, one electron beam is deflected so that a raster of 16 lines is sequentially drawn one line at a time from the top.

As a result of the above, an electron beam is emitted for a period of 16 hours from the top of the 15 line cathodes 2A to 2Y, and each electron beam is sequentially emitted for one line from the top to the bottom within 15 sections in the vertical direction. As a result, the electron beam is vertically deflected one line at a time on the screen 9 from the first line at the top end to the 240th line at the bottom end, and a total of 240 lines of raster are drawn.

The electron beam thus vertically deflected is horizontally deflected by 180 degrees by the control electrode 5 and the horizontal focusing electrode 6.
It is divided into sections and taken out. Figure 5 shows one of these categories. The amount of electron beam passing through each section is controlled by a control electrode 5, and horizontally focused by a horizontal focusing electrode 6 into a single narrow electron beam, which is then controlled by horizontal deflection means described below. The light is then deflected in six steps in the horizontal direction and is sequentially irradiated onto each of the R, G, and B phosphors 20 for two picture elements on the screen 9. FIG. 2 shows the vertical and horizontal divisions. The phosphors corresponding to each of 15a to 15n of the control electrode 5 are R, G, and B for two picture elements, but for convenience of explanation, one picture element is
Let R ₁ , G ₁ , and B ₁ be R ₂ , G ₂ , and B ₂ .

Next, the horizontal deflection drive circuit 41 is composed of a horizontal deflection counter (11 bits), a memory 29 storing horizontal deflection signals, and a DA converter 38. The input pulse to the horizontal deflection drive circuit 41 is synchronized with the vertical synchronizing signal V and the horizontal synchronizing signal H, as shown in FIG. 7, and uses a pulse 5H having a repetition frequency six times that of the horizontal synchronizing signal H.

The horizontal deflection counter 28 is reset by the vertical synchronizing signal V and counts horizontal six times pulses 6H. This horizontal deflection counter 28 is
6 times during 1H, 240H x 6/H = 1440 during 1V
The count output is supplied to an address in the memory 29. The memory 29 outputs horizontal deflection signal data (here, 8 bits) according to the address, and the DA converter 38 outputs the data of the 11th horizontal deflection signal.
It is converted into horizontal deflection signals such as h and h' shown in the figure. This circuit has a memory address for storing horizontal deflection signals corresponding to each of 6 x 240 lines, and by storing regular 6 pieces of data for each line in the memory, 6 step waves are generated in 1H period. horizontal deflection signals can be obtained.

This horizontal deflection signal is a pair of horizontal deflection signals h and h' that change in 6 steps as shown in FIG. 7, both have a center voltage of V ₇ , and h gradually decreases.
h' increases in sequence and changes in opposite directions. These horizontal deflection signals h, h' are applied to electrodes 18 and 18' of the horizontal deflection electrode 7, respectively.
As a result, each of the horizontally divided electron beams is transmitted to the R, G, B of the screen 9 during each horizontal period.
It is horizontally deflected so that R, G, and B (R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ ) phosphors are sequentially irradiated with H/6 each. Thus, in each line raster, the electron beam is R ₁ ,
Each phosphor 20 of G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ is sequentially irradiated with light.

Therefore, an electron beam is applied to each horizontal section of each line.
A color television image can be displayed on the screen 9 by modulating the video signals R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ .

Next, the modulation control portion of the electron beam will be explained.

First, the composite video signal applied to the television signal input terminal 23 is applied to the color demodulation circuit 30,
Here, the color difference signals of R-Y and B-Y are demodulated,
G-Y color difference signals are matrix-synthesized, and further, they are combined with the luminance signal Y to generate R, G, B
Each primary color signal (hereinafter referred to as R, G, B video signal)
is output. Those R, G, and B video signals are
180 sample and hold circuit sets 31a to 31n
added to. Each sample and hold circuit set 31a
~31n are for R ₁ , G ₁ , B ₁ , R ₂ , respectively.
It has 6 sample and hold circuits for G ₂ and B ₂ . These sample and hold outputs are applied to holding memory sets 32a-32n, respectively.

On the other hand, the reference clock oscillator 33 is constituted by a PLL (phase locked loop) circuit, etc., and in this embodiment generates a reference clock 6f _SC that is six times the color subcarrier f _SC and a reference clock 2f _SC that is twice the color subcarrier f SC. . The reference clock is controlled to always have a constant phase with respect to the horizontal fixed signal H.
The reference clock 2f _SC is added to the deflection pulse generation circuit 42, and the signals 6H and H/
6 signal switching pulses r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ are obtained. On the other hand, the reference clock 6f〓 _C is applied to the sampling generation circuit 34, where it is delayed by one clock period by a shift register, etc., so that the effective horizontal scanning period (approximately 50 μsec) of the horizontal period (63.5 μsec) is delayed. In between, 1080 sampling pulses R _a1 to R _o2 are generated sequentially, and then 1
Transfer paths t are generated. These sampling pulses R _a1 to _{R o2} correspond to each picture element when one line of the video to be displayed is divided into 360 picture elements in the horizontal direction, and their positions are always constant with respect to the horizontal synchronizing signal H. controlled so that

These 1080 sampling pulses R _a1 to B _o2 are each connected to 180 sample and hold circuit sets 31a.
.about.31n, and as a result, when one line is divided into 180 circuits, each sample-and-hold circuit group 31a to 31n has 2 picture elements each.
Each video signal of R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ is individually sampled and held. The sample held 180 pairs of R ₁ , G ₁ , B ₁ R ₂ , G ₂ , B ₂
After the sample and hold for one line is completed, the video signals are transferred all at once to 180 sets of memories 32a to 32n by a transfer pulse t, where they are held for the next horizontal period. This retained R ₁ , G ₁ , B ₁ ,
The signals of R ₂ , G ₂ , and B ₂ are sent from the switching circuit 35a to
35n. Switching circuit 35a~
35n is composed of tristate or analog gates each having individual input terminals for R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ and a common output terminal that sequentially switches and outputs them. It is.

The output of each switching circuit 35a to 35n is
180 sets of pulse width modulation (PWM) circuits 37a to 3
7n, and here, the reference pulse signal is pulse width modulated according to the magnitude of the sampled and held R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ video signals and is output. It is desirable that the repetition period of the reference pulse signal is sufficiently smaller than the pulse width of the signal switching pulses r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ , for example, 1:10 to 1:1. A ratio of about 1:100 is used.

The output of the pulse width modulation circuits 37a to 37n is used as a control signal for modulating the electron beam to the 180 conductive plates 15a to 15 of the control electrode 5 of the display element.
n separately. Each of the switching circuits 35a to 35n receives a switching pulse r ₁ applied from the switching pulse generation circuit 36,
Switching is controlled simultaneously by g ₁ , b ₁ , r ₂ , g ₂ , and b ₂ . The switching pulse generation circuit 36 generates a signal switching pulse from the deflection pulse generation circuit 42 mentioned above.
controlled by r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ ,
Each horizontal period is divided into six, and the switching circuits 35a to 35n are switched by H/6, and R ₁ , G ₁ , B ₁ ,
Switching signals r _{1 ,} g ₁ , b _{1 ,} r ₂ , g _{2 ,} b Generate ₂ .

What should be noted here is that the switching circuit 3
R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ in 5a to 35n
video signal supply switching and horizontal deflection drive circuit 4
The horizontal deflection of the electron beams R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ irradiated onto the phosphor by 1 is synchronously controlled so that they completely match both in timing and order. That's true. As a result, when the electron beam R ₁ is irradiated with the phosphor, the irradiation amount of the electron beam is controlled by the R ₁ video signal, and the same applies to G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ . controlled, R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ of each picture element
The emission of each phosphor corresponds to the R ₁ , G ₁ , B ₁ , R ₂ ,
Each picture element is controlled by the G ₂ and B ₂ video signals, and each picture element is displayed by emitting light according to the input video signal. This control is performed simultaneously for 180 sets (2 picture elements each) for one line, and an image of 360 picture elements per line is displayed, and an additional 240 picture elements are displayed.
This is done sequentially for the minute lines starting from the upper line, and one image is displayed on the screen 9.

The above operations are repeated for each field of the input television signal, and as a result,
The screen 9 is similar to a normal television receiver.
The television footage of the video is shown above.

Problems to be Solved by the Invention In the image display device as described above, the landing position of each electron beam on the screen is strictly determined, and positional deviation in the vertical direction is
If the raster interval is short, it appears as an increase or decrease in brightness due to clustering or opening.

Such a shift in the landing position of the electron beam is thought to be caused by changes in the vertical deflection waveform over time or the expansion and contraction over time of each electrode that makes up the display element. In order to maintain this, it is necessary to make the deflection waveform amplification circuit extremely precise and to use electrode materials that have very little expansion and contraction, which lead to increased power consumption and cost. Therefore, it is not practical.

Means for Solving the Problems In the present invention, at least one of the electrodes arranged closer to the screen than the vertical deflection electrode of the display element is provided outside the effective screen, electrically separated from the electrode inside the effective screen. Two electron beam position detection electrodes are provided, one of which has a vertically long wedge-shaped electron beam passing hole, and the other one has a similar wedge-shaped electron beam passing hole with the vertical direction reversed. By making the amounts of electron beams flowing into both electrodes in a complementary relationship with each other, the vertical landing position of the electron beam can be detected, and the electron beam can be detected when the electron beam is irradiated onto the screen and at the normal position. The signal from the beam detection electrode is stored in a memory circuit, and during actual operation, the signal from the electron beam position detection electrode is compared with the signal stored in the memory circuit, and the difference is detected by a part of the display element drive circuit. It provides feedback to the

Effect: According to the image display device of the present invention, there are two electron beam position detection electrodes having wedge-shaped electron beam passing holes that are opposite to each other in the vertical direction, and these electrodes are unaffected by increases and decreases in the amount of electron beams. By obtaining an electron beam position signal, comparing the regular electron beam position signal with the electron beam position signal during actual operation, and feeding back the difference to a part of the display element drive circuit, the electron beam position signal on the screen can be adjusted. The vertical landing position of the beam is controlled so as to be always maintained at a normal position.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a vertical focusing electrode 3' is disposed on the screen side of the vertical deflection electrode 4 of the display element.
Two electron beam position detection electrodes 50, 50' electrically separated from the electrode 3' are arranged outside the effective screen of the electron beam. These electrodes 50, 50' are electrically isolated from each other and have vertically long wedge-shaped electron beam passing holes (slits) 51, 51' with a length equivalent to the distance between the pair of vertical deflection electrodes 4. , the slits are formed in the shape of opposite wedges in the vertical direction between the electrodes 50 and 50'.

In order to detect the landing position in the vertical direction, a pilot electron beam 52 having a horizontal spread sufficient to obtain a uniform electron density in the horizontal direction of the electrodes 50, 50' is passed through the wedge-shaped slit 5.
1 and 51' are vertically deflected so as to irradiate specific positions, respectively, near the upper and lower ends. in particular,
For example, as shown in Fig. 3, in addition to the period in which an image is displayed in the n-th vertical section Kn, a line cathode driving pulse is generated to display Kn during the vertical retrace period of each field, and the corresponding The vertical deflection waveform is also set so that the electron beam irradiates the vicinity of the upper end of Kn during the vertical retrace period of the mth field, m+
In the vertical retrace period of the first field, the drive waveform may be such that the electron beam irradiates the vicinity of the lower end of Kn.

In this way, the electron beam position detection electrode 50,
The beam electrons irradiated onto 50' become currents I ₁ and I ₂ and are guided to current-voltage conversion circuits 53 and 53', where they are converted into voltages E ₁ and E ₂ , as shown in FIG. 1b. Ru. Here, the currents I ₁ and I ₂ are inversely proportional to the amount of the electron beam passing through the wedge-shaped slit, and as the beam irradiation position changes in the vertical direction, I ₁
They have a complementary relationship: if I increases, I ₂ decreases, and if I ₁ decreases, I ₂ increases. Therefore, y=
(I ₁ − I ₂ )/(I ₁ + I ₂ ), that is, y=(E ₁ −
E ₂ )/(E ₁ + E ₂ ), E ₁ = E ₂
If E ₁ > E ₂ , the beam is biased upward (y >
0), and conversely, if E ₁ < E ₂ , it is biased downward (y=0)
I can know that. Furthermore, even if the beam irradiation amount increases or decreases by k times (k is a positive number) due to changes in the emission current of the electron source over time, y=
(kE ₁ −kE ₂ )/(kE ₁ +kE ₂ )=(E ₁ −E ₂ )/(E ₁
+E ₂ ), and it is possible to obtain an irradiation position signal without being affected by an increase or decrease in the amount of electron beam irradiation.

Now, a feedback system for compensating the landing position of the electron beam can be constructed as shown in FIG. current-voltage conversion circuit 53,
The pulse signals E ₁ and E ₂ obtained at 53' are sent to circuits 54,
After sampling and holding at 54', it is time-divisionally D-A converted at A/D converter 55, and then sent to CPU 56.
The data is stored in the memory 57 via. This stored digital data is converted into position data by the calculation of the CPU, and is compared with initial position data stored in the memory 57 in a similar manner when the landing position is optimally adjusted. if
Position data D ₂ of the electron beam irradiated to the upper end of K _o
and the position data of the electron beam irradiated to the bottom edge D ₃
However, compared with each initial position data D ₀ and D ₁ ,
D ₂ > D ₀ and D ₃ > D ₁ or D ₂ < D ₀ and D ₃ <
If D ₁ , it is determined that the entire K _o has changed up and down as shown in Figure 4a, and D ₂ > D ₀ and D ₃ < D ₁
Or if D ₂ <D ₀ and D ₃ >D ₁ , then Figure 4b
It is determined that the amplitude of K _o has expanded and contracted as shown in .

Then, depending on each case, the data difference is processed into data of the same magnification in the CPU 56 and added or subtracted from the vertical deflection data for K _o stored in the deflection data memory 27. A/D
A series of processes up to addition and subtraction of the converted data are performed during the vertical retrace period, and the corrected data is stored in memory 2.
7 in a location different from the initial deflection data. Then, when displaying the image of K _o next time, the corrected vertical deflection data is read out from the memory 27 and applied to the vertical deflection electrodes as a vertical deflection signal after D/A conversion. Feedback is applied to maintain the beam irradiation position.

As described above, it is possible to control the vertical irradiation position of the electron beam so that it is always maintained at the normal position at the time of optimum adjustment.

Effects of the Invention As described above, according to the present invention, the vertical landing position of the electron beam irradiated onto the screen is detected by the electron beam position detection electrode disposed inside the display element, and the electron beam is The signal from the electron beam position detection electrode stored in the memory circuit when the electron beam is irradiated to the regular position of the electron beam is compared with the signal from the electron beam position detection electrode during actual operation, and the difference is detected by the display element drive circuit. By feeding back a part of the screen, it is possible to control the electron beam so that it is always irradiated at the correct position on the screen, and it is possible to control the electron beam so that it is always irradiated at the correct position on the screen. It is possible to compensate for changes in the landing position of the electron beam in the vertical direction caused by expansion and contraction, and to maintain a constant raster interval in the vertical direction to prevent uneven brightness.

[Brief explanation of drawings]

FIGS. 1a and 1b are enlarged exploded perspective views showing the arrangement of electron beam position detection electrodes of an image display element used in an image display device according to an embodiment of the present invention, and a block diagram for explaining the electron beam position detection principle thereof. 2 is a block diagram showing the configuration of the feedback system, FIG. 3 is a waveform diagram showing the vertical deflection waveform and line cathode drive pulse waveform for irradiating the pilot electron beam, and FIG. An enlarged view to explain the vertical change in the electron beam position, FIG. 5 is an exploded perspective view of an image display element used in a conventional image display device, and FIG. 6 is an enlarged view of the fluorescent screen of the image display element. 7 is a block diagram showing the basic configuration of the drive circuit of the image display element, FIG. 8 is a waveform diagram for explaining the operation of the vertical deflection drive, and FIG. 9 is a waveform diagram for explaining the operation of the line cathode drive circuit. Figure 10 is a waveform diagram of each drive signal.
FIG. 1 is a waveform diagram for explaining the operation of the horizontal deflection drive circuit. 2, 2 I to 2 Y... Line cathode, 3'... Vertical focusing electrode, 4... Vertical deflection electrode, 5... Beam flow control electrode, 7... Horizontal deflection electrode, 9... Screen,
10... Slit, 20... Phosphor, 23... Input terminal, 24... Synchronous separation circuit, 25... Vertical deflection counter, 26... Line cathode drive circuit, 27
...Memory, 28...Horizontal deflection counter, 2
9...Memory, 30...Color demodulation circuit, 31a-3
1n...Sample hold circuit, 32a to 32n
...Memory, 33...Reference clock oscillator, 34...
...Sampling pulse generation circuit, 35a to 35n
...Switching circuit, 36...Switching pulse generation circuit, 37a to 37n...PWM circuit,
38...D/A converter, 39...D/A converter,
40... Vertical deflection drive circuit, 41... Horizontal deflection drive circuit, 42... Deflection pulse generation circuit, 50,
50'...Electron beam position detection electrode, 51,5
1'... Wedge-shaped slit, 53, 53'... Current-voltage conversion circuit, 54, 54'... Sample/hold circuit, 55... A/D converter, 56... CPU,
57...Memory.

Claims (1)

[Scope of Claims] 1. A screen having a plurality of line cathode electron beam generation sources, a phosphor that emits light when irradiated with the electron beams, and a focusing device that focuses the electron beams generated by the electron beam generation sources. a display element having an electrode, an electrostatic deflection electrode that deflects the electron beam on the way to the screen, and a control electrode that controls the emission intensity by controlling the amount of the electron beam irradiated to the screen. At least one of the electrodes arranged closer to the screen than the vertical deflection electrode of the display element has two electron beam detection electrodes outside the image display area, which are electrically separated from the electrodes in the image display area. is placed, and the above 2
a calculation means for determining the vertical irradiation position of the electron beam based on the amount of electrons by establishing a mutually complementary relationship between the amounts of electrons irradiated and flowing into the electrodes; and a calculation means for determining the irradiation position of the electron beam based on the output of the calculation means. An image display device comprising: means for controlling an image. 2. One of the two electron beam detection electrodes is provided with a vertically long wedge-shaped electron beam passing hole, and the other electrode is provided with a similar wedge-shaped electron beam passing hole with the vertical direction reversed. An image display device according to claim 1. 3 The signal obtained from the electron beam detection electrode when the electron beam is irradiated on the screen and at the regular position is stored in advance in a memory circuit, and the signal obtained from the electron beam detection electrode and the signal obtained from the electron beam detection electrode when displaying an image is stored in the memory circuit. 3. The image display device according to claim 1, further comprising means for comparing the output signal with a predetermined signal and controlling the difference as feedback to a part of the display element drive circuit.